Tools: set multiple variable with fw_setenv utility

Add a sort of batch mode to fw_setenv, allowing to set
multiple variables in one shot, without updating the flash after
each set as now. It is added the possibility to pass
a config file with a list of pairs <variable, value> to be set,
separated by a TAB character.

Signed-off-by: Stefano Babic <sbabic@denx.de>
diff --git a/tools/env/fw_env.h b/tools/env/fw_env.h
index c04da54..8130fa1 100644
--- a/tools/env/fw_env.h
+++ b/tools/env/fw_env.h
@@ -50,5 +50,9 @@
 extern int   fw_printenv(int argc, char *argv[]);
 extern char *fw_getenv  (char *name);
 extern int fw_setenv  (int argc, char *argv[]);
+extern int fw_parse_script(char *fname);
+extern int fw_env_open(void);
+extern int fw_env_write(char *name, char *value);
+extern int fw_env_close(void);
 
 extern unsigned	long  crc32	 (unsigned long, const unsigned char *, unsigned);